A filtration method is a common way to separate solids and liquids. A filter having smaller holes is used to intercept larger solids. The smaller solid and liquid particles pass through the holes. Separating solids and the liquids is thus achieved. However, the conventional filtration method faces a problem where the small holes of the filter are easily blocked by the separated solids in the filtrated solution. Thus the operating lifespan of the filter is very short. Additionally, the small blocked holes need to be washed in order to refresh their ability to function. This requires additional equipment and process and it increases the operating costs. In addition, to increase filtering speed, a high speed-rotating pump is used to produce a compressing or vacuuming process. However, operating the pumping consumes more energy and increases operating costs.